Beta-lactam antibiotics and viridans group streptococci / Antibióticos beta-lactámicos y estreptococos grupo viridans

Abstract The aim of this review is to present an update on the susceptibility of viridans groupstreptococci (VGS) to -lactam antimicrobials, with emphasis on the Argentinean scenario. VGSare a heterogeneous group including five groups of species, each one exhibiting peculiar sus-ceptibility patterns to penicillin (PEN). Species of the Streptococcus mitis group are frequentlynonsusceptible to PEN. PEN resistance is associated with changes in PEN-binding proteins. InArgentina, one to two thirds of VGS are nonsusceptible to PEN. Third generation cephalosporinsand carbapenems are currently more effective in vitro than PEN against VGS. Mortality was asso-ciated to nonsusceptibility to PEN in at least two studies involving patients with bacteremiacaused by VGS. Treatment of endocarditis due to VGS should be adjusted/to the PEN suscepti-bility of the isolates. Vancomycin may be an alternative choice for treating endocarditis causedby PEN-resistant isolates (MIC 4 g/ml).

Resumen El objetivo de esta revisión es presentar una actualización sobre la sensibilidad de los estreptococos del grupo viridans (EGV) a los antimicrobianos p-lactámicos, con énfasis en el escenario argentino. Los EGV son un grupo heterogéneo que incluye cinco grupos de especies, y cada una presenta su patrón especial de sensibilidad a la penicilina (PEN). Las especies del grupo Streptococcus mitis, con mayor frecuencia, no son sensibles a la PEN. La resistencia a la PEN se asocia con cambios de las proteínas ligadoras de PEN. En la Argentina, de uno a dos tercios de los EGV no son sensibles a la PEN. Las cefalosporinas de tercera generación y los carbapenemes son actualmente más eficaces in vitro que la PEN contra los EGV. La mortalidad se asoció con la no sensibilidad a la PEN en al menos dos estudios de pacientes con bacteriemia por EGV. El tratamiento de las endocarditis por EGV debe ajustarse según la sensibilidad a la PEN de los aislados. La vancomicina podría ser una elección alternativa para el tratamiento de las endocarditis por cepas resistentes a PEN (CIM >4 ^g/ml).

Beta-lactam antibiotics and viridans group streptococci.

The aim of this review is to present an update on the susceptibility of viridans group streptococci (VGS) to ß-lactam antimicrobials, with emphasis on the Argentinean scenario. VGS are a heterogeneous group including five groups of species, each one exhibiting peculiar susceptibility patterns to penicillin (PEN). Species of the Streptococcus mitis group are frequently nonsusceptible to PEN. PEN resistance is associated with changes in PEN-binding proteins. In Argentina, one to two thirds of VGS are nonsusceptible to PEN. Third generation cephalosporins and carbapenems are currently more effective in vitro than PEN against VGS. Mortality was associated to nonsusceptibility to PEN in at least two studies involving patients with bacteremia caused by VGS. Treatment of endocarditis due to VGS should be adjusted/to the PEN susceptibility of the isolates. Vancomycin may be an alternative choice for treating endocarditis caused by PEN-resistant isolates (MIC≥4µg/ml).

Epidemiology of Invasive Infections Caused by Streptococcus agalactiae in Argentina.

In recent years, an increase in the number of cases of invasive infections due to Streptococcus agalactiae (group B Streptococcus [GBS]) in adults has been reported. During 2014 and 2015, a multicentric, observational, and prospective study, including 40 health centers, was developed to describe the phenotypic and genotypic characteristics of GBS isolates circulating in Argentina and to analyze the clinical and demographic characteristics of patients with invasive infections. We recovered 162 invasive (GBSi) isolates from adult patients (n = 130, 80.2%), neonates (n = 24, 15%), and children below 18 years of age (n = 8, 4.8%), and colonizing (GBSc) isolates were recovered in prenatal GBS screening. GBS infection in adults was associated with underlying diseases, mainly diabetes mellitus. All isolates were penicillin susceptible. Resistance rates to erythromycin (25%) and clindamycin (26%) among the GBSc isolates were significantly higher than those from GBSi strains (17.3% and 16.1%, respectively); by contrast, levofloxacin resistance was significantly higher in GBSi isolates (14.8% vs. 7%). Serotype Ia was the most frequent in neonates and Ib was most frequent in adults. Serotypes Ia and III were prevalent in GBSc isolates. The increase of levofloxacin resistance was associated with the presence of a serotype Ib clone. This work emphasizes the need for GBS infection surveillance studies to implement correct treatments and adequate prevention strategies.

Resistance to ß-lactams in Streptococcus pneumoniae.

Streptococcus pneumoniae is an important causal agent of pneumonia, meningitis, sepsis, bacteremia, and otitis media. Penicillin resistance rates in S. pneumoniae have remained stable in Argentina in the last years. In the late '90s more isolates with MIC of penicillin ≥2µg/ml were observed; however, their frequency has decreased in recent years. The phenotypic expression of penicillin resistance is due to a modification in penicillin-binding proteins associated with a mosaic structure in the coding genes. The expansion of successful resistant clones varies among the different regions and is influenced by the use of antibiotics, vaccines, particularly conjugated ones, as well as population density. Parenteral treatment with high doses of penicillin G continues to be effective for the treatment of pneumonia and bacteremia, oral aminopenicillins for otitis media and sinusitis and third generation cephalosporins for meningitis.

Resistencia a los β -lactámicos en enterococos / Resistance to β-lactams in enterococci

Enterococci are intrinsically resistant to several antimicrobial classes and show a great ability to acquire new mechanisms of resistance. Resistance to β-lactam antibiotics is a major concern because these drugs either alone or in combination are commonly used for the treatment of enterococcal infections. Ampicillin resistance, which is rare in Enterococcus faecium occurs in most of the hospital-associated Enterococcus faecium isolates. High-level resistance to ampicillin in E. faecium is mainly due to the enhanced production of PBP5 and/or by polymorphisms in the beta subunit of this protein. The dissemination of high-level ampicillin resistance can be the result of both clonal spread of strains with mutated pbp5 genes and resistance horizontal gene transfer.

Los enterococos son intrínsecamente resistentes a varias clases de antimicrobianos y presentan una gran capacidad para adquirir mecanismos de resistencia. La resistencia a los antibióticos p-lactámicos es preocupante porque estos fármacos solos o combinados se usan comúnmente para el tratamiento de las infecciones enterocócicas. La mayoría de los aislamientos hospitalarios de Enterococcus faecium presentan resistencia a la ampicilina, la cual es rara en Enterococcus faecalis. El alto nivel de resistencia a la ampicilina en E. faecium se debe principalmente a la hiperproducción de PBP5 y/o a polimorfismos en la subunidad beta de esta proteína. La propagación de esta resistencia puede deberse tanto a la diseminación clonal de cepas con genes pbp5 mutados como a la transferencia horizontal de genes.

Fluoroquinolone-Resistant Streptococcus agalactiae Invasive Isolates Recovered in Argentina.

Background: Streptococcus agalactiae or group B Streptococcus (GBS) is an important pathogen in neonates and nonpregnant individuals. Epidemiological studies of GBS resistance to fluoroquinolones (FQs) in Latin America are scarce. This study aimed to determine the local prevalence of FQ resistance in the frame of a national, prospective multicenter study of invasive GBS infections and to investigate mechanisms of resistance, serotype distribution, and clonal relationships among resistant isolates. Methods: From July 2014 to July 2015, 162 invasive GBS isolates were collected from 86 health care centers in 32 Argentinean cities. All isolates were screened for FQ nonsusceptibility using a five-disc scheme: levofloxacin (LVX), ciprofloxacin, norfloxacin (NOR), ofloxacin, and pefloxacin (PF). LVX minimal inhibitory concentration (MIC) was determined by the agar dilution method. Sequencing of internal regions of gyrA and parC genes was performed. Capsular typing and genetic characterization of nonsusceptible isolates were assessed by latex agglutination, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Results: Twenty-four of one hundred sixty-two GBS isolates exhibited no inhibition zones to all tested FQs with an MIC range of 16-32 mg/L for LVX, and one isolate with MIC = 1 mg/L showed no inhibition zones around NOR and PF discs. In all resistant isolates, point mutations were detected in both genes. Serotype Ib was prevalent (88%). One PFGE type accounted for 84% of the FQ-resistant isolates and belonged to serotype Ib, sequence type 10. Conclusions: The prevalence of FQ resistance was 14.8% likely to be associated with dissemination of an ST10/serotype Ib clone. The unexpected high rate of resistance emphasizes the relevance for continuous surveillance of GBS epidemiology and antibiotic susceptibility.

Argentinian multicenter study on urinary tract infections due to Streptococcus agalactiae in adult patients.

INTRODUCTION: Streptococcus agalactiae (group B streptococcus, GBS) is a recognized urinary pathogen both in males and pregnant or non-pregnant women. Data regarding GBS serotypes recovered from urinary tract infections (UTIs) are scarce. The aim of this study was to describe the clinical and microbiological characteristics of UTIs caused by GBS in adult patients in Argentina. METHODOLOGY: A prospective multicenter study involving 86 centers was conducted in Argentina between July 1st, 2014 and June 30th, 2015. Antimicrobial susceptibility and serotype distribution of GBS isolated from the urinary tract of adult patients were determined. Susceptibility tests were performed by the disk diffusion and/or agar dilution methods. Epidemiological and clinical characteristics of the patients were considered to identify associated comorbilities. RESULTS: Seven hundred and one GBS were sent to the reference laboratory in the above mentioned period, however, only 211 fulfilled our selection criteria (demographic data availability, underlying diseases reported, colony counts greater than 105 CFU/mL, single organism isolated from the urine sample). No penicillin-resistant GBS was found but fluoroquinolone resistance was high (12.8%), especially among GBS isolated from men and non-pregnant women. UTIs due to GBS were associated to underlying diseases in men and non-pregnant women, particularly diabetes mellitus. Most of the isolates showed serotypes Ia and III. CONCLUSIONS: GBS are still susceptible to penicillin but fluoroquinolone resistance is a growing concern, at least in Argentina. There are underlying conditions that could be associated to urinary infections caused by GBS.

Resistance to ß-lactams in enterococci.

Enterococci are intrinsically resistant to several antimicrobial classes and show a great ability to acquire new mechanisms of resistance. Resistance to ß-lactam antibiotics is a major concern because these drugs either alone or in combination are commonly used for the treatment of enterococcal infections. Ampicillin resistance, which is rare in Enterococcus faecalis, occurs in most of the hospital-associated Enterococcus faecium isolates. High-level resistance to ampicillin in E. faecium is mainly due to the enhanced production of PBP5 and/or by polymorphisms in the beta subunit of this protein. The dissemination of high-level ampicillin resistance can be the result of both clonal spread of strains with mutated pbp5 genes and horizontal gene transfer.

Infecciones urinarias por Streptococcus agalactiae y Staphylococcus saprophyticus y embarazo / Urinary tract infections due to Streptococcus agalactiae and Staphylococcus saprophyticus and pregnancy / Infecções urinárias por Streptococcus agalactiae y Staphylococcus saprophyticus e gravidez

Distintos autores difieren en la mayor o menor prevalencia de las infecciones urinarias (IU) por Streptococcus agalactiae y Staphylococcus saprophyticus en mujeres embarazadas (ME) y no embarazadas (NE). Se realizó un estudio retrospectivo, comparativo, de cohortes con el objetivo de evaluar la frecuencia de IU por S. agalactiae y S. saprophyticus en ME asintomáticas pertenecientes a centros de atención primaria de la salud del Municipio de La Plata (CAPS) entre 2008 y 2016 y se la comparó con la de NE sintomáticas en edad fértil, no internadas, que asistieron al Hospital "San Roque" (HSR) entre 2014 y 2017. Se procesaron 2.378 orinas de ME que concurrieron a las CAPS. De ese total, 201 fueron positivas (8,5%), el 10,4% de las mismas (n: 21) correspondieron a S. agalactiae y el 10,0% a S. saprophyticus (n: 20). En el 54% se aisló Escherichia coli. El total de urocultivos en la población de NE fue de 2.281 y 526 fueron positivos (23,1%): 7 correspondieron a S. agalactiae (1,3%), 18 a S. saprophyticus (3,4%) y el 78% a E. coli. En conclusión, la frecuencia de aislamiento de S. agalactiae y S. saprophyticus fue significativamente mayor en la población de ME pertenecientes a las CAPS respecto de las NE estudiadas en el HSR.

Several authors differ in the greater or lesser prevalence of urinary tract infections (UTI) due to Streptococcus agalactiae and Staphylococcus saprophyticus in pregnant women (PW) and non-pregnant women (NPW). A retrospective, comparative, cohort study was carried out with the objective of evaluating the frequency of UTI by S. agalactiae and S. saprophyticus in asymptomatic PW from primary care centers of the Municipality of La Plata (PCC) between 2008 and 2016 and comparing it with symptomatic NPW in a fertile age, not hospitalized women, who attended the "San Roque" Hospital (HSR) between 2014 and 2017. A total of 2,378 urine samples from PW assisted at the PCC were processed. Two hundred and one were positive (8.5%); 10.4% of them (n: 21) corresponded to S. agalactiae and 10.0% to S. saprophyticus (n: 20). Escherichia coli was isolated in 54%. The total of urine cultures in the population of NPW of the HSR was 2,281 and 526 were positive (23.1%): 7 corresponded to S. agalactiae (1.3%), 18 to S.saprophyticus (3.4%) and 78% to E. coli. In conclusion, the frequency of isolation of S. agalactiae and S. saprophyticus was significantly higher in the population of PW belonging to the PCC than in the NPW studied in the HSR.

Diferentes autores diferem na maior ou menor prevalência das infecções do trato urinário (ITU) devido a Streptococcus agalactiae e Staphylococcus saprophyticus em mulheres grávidas (MG) e mulheres não grávidas (NG). Realizou-se um estudo retrospectivo e comparativo de coortes com o objetivo de avaliar a frequência de ITU por S.agalactiae e S.saprophyticus em MGs assintomáticas pertencentes a salas de atendimento primário do município de La Plata (CAPS) entre 2008 e 2016 e compará-lo com NG sintomáticas em idade fértil, não hospitalizadas, que frequentaram o Hospital "San Roque" (HSR) entre 2014 e 2017. Foram processadas 2.378 amostras de urina de MG atendidas nas CAPS. Desse total, 201 foram positivos (8,5%), 10,4% das mesmas (n: 21) corresponderam a S. agalactiae e 10,0% a S. saprophyticus (n: 20). Escherichia coli foi isolada em 54%. As culturas de urina total na população de NG foram de 2.281 e 526 foram positivas (23.1%): 7 correspondem a S.agalactiae (1.3%), 18 a S.saprophyticus (3.4%) e 78% para E. coli. Em conclusão, a frequência de isolamento de S. agalactiae e S. saprophyticus foi significativamente maior na população de MG pertencente às CAPS do que as NG estudadas no HSR.

Susceptibility to β-lactams in β-hemolytic streptococci / Sensibilidad a los β-lactámicos en estreptococos β-hemolíticos

Group A (GAS), B (GBS), c (GCS) and G (GGS) β-hemolytic streptococci are important human pathogens. They cause infections of different severity and frequency. Nowadays, after 70 years of use, penicillin is still universally active against GAS, GCS and GGS. However, therapeutic failures have been recorded in 2-28% of pharyngitis cases (median: 12%) attributable to different causes. By contrast, some GBS with reduced susceptibility to penicillin have been described, especially in Japan. In this group of bacteria, it is important to highlight that confirmation by reference methods is mandatory when decreased susceptibility to penicillin is suspected as well as checked for the detection of the mechanisms involved.

Los estreptococos β-hemolíticos de los grupos A (GAS), B (GBS), C (GCS) y G (GGS) son importantes patógenos humanos. Ellos producen infecciones de diversa gravedad y frecuencia. Aún después de más de 70 años de uso, la penicilina sigue siendo activa in vitro frente al 100% de los GAS, GCS y GGS. No obstante se han producido fallas terapéuticas entre el 2-28% de los casos de faringitis (media: 12%), atribuibles a diversas causas. En cambio se han descrito aislados de GBS con sensibilidad reducida a la penicilina, especialmente en Japón. Es importante que toda sospecha de sensibilidad disminuida a la penicilina en este grupo de bacterias sea confirmada por los métodos de referencia y comprobada mediante la detección de los mecanismos involucrados.

[Susceptibility of Streptococcus pyogenes isolated from invasive infections to trimethoprim-sulfamethoxazole]. / Sensibilidad a trimetoprima-sulfametoxazol de Streptococcus pyogenes aislados de infecciones invasivas.

It is erroneously believed that group A streptococci (GAS) are universally resistant to trimethoprim-sulfamethoxazole (TMS). This is mainly because media commonly used for in vitro determination of susceptibility to antibiotics contain thymidine, a nucleoside that antagonizes the antibiotic effect of TMS. The objective of this work was to determine EGA sensitivity to TMS in the presence and absence of thymidine. To this aim, 95 GAS isolates obtained from clinical tissues with i nvasive infections were analyzed. Susceptibility tests were performed by diffusion with TMS discs in Mueller Hinton agar supplemented either with 5% sheep blood or with 5% lysed equine blood (MH-LEB). Lysed equine blood contains thymidine phosphorylase, which degrades this nucleoside. Epsilometry (Etest) was used as gold standard. Quality controls with Enterococcus faecalis strain ATCC 29212 were satisfactory with both media. A 100% sensitivity to TMS was found in MH-SEL whereas 6 isolates (6.3%) resulted resistant in MH-SC; only one of them was found to have intermediate susceptibility by Etest (MIC > 1.5/28 υg/ml). The genetic determinants most frequently associated to TMS resistant EGA were not found in this isolate. Probably, if more accurate GAS-specific cut-off points were established for diffusion, the correlation with dilution methods or with the Etest could be improved, even employing MH-SB.

Sensibilidad a trimetoprima-sulfametoxazol de Streptococcus pyogenes aislados de infecciones invasivas / Susceptibility of Streptococcus pyogenes isolated from invasive infections to trimethoprim-sulfamethoxazole

Se cree erróneamente que los estreptococos del grupo A (EGA) son universalmente resistentes a trimetoprima-sulfametoxazol (TMS). Esto se debe a que la timidina presente en los medios habitualmente usados para determinar sensibilidad in vitro a antibióticos antagoniza el efecto antibiótico de TMS. El objetivo de este trabajo fue determinar la sensibilidad de EGA a TMS, en presencia y ausencia de timidina. A tal fin, fueron analizados 95 aislamientos clínicos obtenidos de tejidos normalmente estériles con infección invasiva por EGA. La pruebas de sensibilidad por difusión con discos de TMS fueron realizadas en agar Mueller Hinton adicionado ya sea con 5% de sangre de carnero (MH-SC) o con 5% de sangre equina lisada (MH-SEL). La sangre equina lisada contiene timidina fosforilasa, que degrada este nucleósido. Como método de referencia se utilizó la epsilometría (Etest). El control de calidad con la cepa Enterococcus faecalis ATCC 29212 fue satisfactorio para ambos medios. La sensibilidad a TMS por difusión fue 100% en MH-SEL; en agar MH-SC 6 (6.3%) aislamientos resultaron resistentes; por Etest todos fueron sensibles, excepto uno de esos seis que presentó sensibilidad intermedia (CIM = 1.5/28.5 μg/ml). En este aislamiento no se encontraron las mutaciones genéticas de EGA más frecuentemente asociadas a resistencia a TMS. Probablemente, si se establecieran mejores puntos de corte para difusión, específicos para EGA, podría optimizarse la correlación con métodos de dilución o con Etest, aun empleando MH-SC.

It is erroneously believed that group A streptococci (GAS) are universally resistant to trimethoprim-sulfamethoxazole (TMS). This is mainly because media commonly used for in vitro determination of susceptibility to antibiotics contain thymidine, a nucleoside that antagonizes the antibiotic effect of TMS. The objective of this work was to determine EGA sensitivity to TMS in the presence and absence of thymidine. To this aim, 95 GAS isolates obtained from clinical tissues with i nvasive infections were analyzed. Susceptibility tests were performed by diffusion with TMS discs in Mueller Hinton agar supplemented either with 5% sheep blood or with 5% lysed equine blood (MH-LEB). Lysed equine blood contains thymidine phosphorylase, which degrades this nucleoside. Epsilometry (Etest) was used as gold standard. Quality controls with Enterococcus faecalis strain ATCC 29212 were satisfactory with both media. A 100% sensitivity to TMS was found in MH-SEL whereas 6 isolates (6.3%) resulted resistant in MH-SC; only one of them was found to have intermediate susceptibility by Etest (MIC > 1.5/28 μg/ml). The genetic determinants most frequently associated to TMS resistant EGA were not found in this isolate. Probably, if more accurate GAS-specific cut-off points were established for diffusion, the correlation with dilution methods or with the Etest could be improved, even employing MH-SB.

Vaginosis bacteriana en embarazadas y su impacto en la prematurez y en el bajo peso al nacer / Bacterial vaginosis in pregnant women and its impact on prematurity and low birth weight / Vaginose bacteriana em mulheres grávidas e seu impacto na prematuridade e baixo peso ao nascer

La vaginosis bacteriana (VB) es un síndrome producido por el desbalance de la microbiota vaginal normal, frecuente en mujeres en edad fértil, incluyendo embarazadas (ME). Los objetivos de este trabajo fueron conocer la prevalencia de VB en el segundo trimestre de embarazo en la población estudiada y su impacto sobre la producción de partos prematuros (PP) y/o de bajo peso al nacer (BPN). Se realizó un estudio retrospectivo, comparativo, de casos y controles, de 315 ME con y sin vaginosis en el segundo trimestre de embarazo entre 2009 y 2016. Se consideraron “casos” a aquellas mujeres afectadas por VB (estadio IV) y “controles” a las que exhibían una microbiota habitual (estadio I). El 20% de las ME presentaron VB (estadio IV). Se registraron 16 BPN (11 entre los 62 casos y 5 entre los 120 controles) (p=0,025). En 16 oportunidades el parto fue prematuro (10 entre los casos y 6 entre los controles) (p=0,007) En total, las dificultades en el parto fueron significativamente más numerosas entre los casos que entre los controles (p=0,009). Al menos en la población estudiada la presencia de vaginosis en el segundo trimestre de las ME estuvo significativamente asociada con PP y/o BPN.

Bacterial vaginosis (BV) is a syndrome produced by the imbalance of the normal vaginal microbiota, common in women of childbearing age including pregnant women (PW). The objectives of this study were to know the prevalence of BV in the second trimester of pregnancy in the population studied and its impact on the production of premature births (PB) and/or low birth weight infants (LBWI). A retrospective, comparative study of cases and controls of 315 PW with and without vaginosis was carried out in the second trimester of pregnancy between 2009 and 2016. Those cases affected by BV (stage IV) were considered “cases”, and “controls” those that exhibited a habitual microbiota (stage I). Twenty percent of PW presented VB (stage IV) and 16 LBWI were recorded (11 among 62 cases and 5 among 120 controls) (p=0.025). On 16 occasions, labour was premature (10 among cases and 6 among controls) (p=0.007). In total, the difficulties in delivery were significantly more numerous among the cases than among the controls (p=0.009), at least in the population studied the presence of vaginosis in the second trimester of the ME was significantly associated with PB delivery and/or LBWI.

A vaginose bacteriana (VB) é uma síndrome produzida pelo desequilíbrio da microbiota vaginal normal, comum em mulheres em idade fértil, incluindo mulheres grávidas (MG). Os objetivos deste estudo foram conhecer a prevalência de VB no segundo trimestre da gravidez na população estudada e seu impacto na produção de nascimentos prematuros (NP) e/ou com baixo peso ao nascer (BPN). Um estudo retrospectivo e comparativo de casos e controles de 315 ME com e sem vaginose foi realizado no segundo trimestre de gravidez entre 2009 e 2016. Os casos afetados por VB (estágio IV) foram considerados “casos”, e “controles” aqueles que exibíam uma microbiota habitual (estagio I). Vinte por cento dos MG apresentaram VB (estagio IV), 16 BPN foram registrados (11 entre 62 casos e 5 entre 120 controles) (p=0,025). Em 16 ocasiões, o parto foi prematuro (10 entre os casos e 6 entre os controles) (p=0,007). No total, as dificuldades no parto foram significativamente mais numerosas entre os casos do que entre os controles (p=0,009). Pelo menos na população estudada a presença de vaginose no segundo trimestre das MG foi significativamente aos à PN e/ou BPN.

Susceptibility to ß-lactams in ß-hemolytic streptococci.

Group A (GAS), B (GBS), C (GCS) and G (GGS) ß-hemolytic streptococci are important human pathogens. They cause infections of different severity and frequency. Nowadays, after 70 years of use, penicillin is still universally active against GAS, GCS and GGS. However, therapeutic failures have been recorded in 2-28% of pharyngitis cases (median: 12%) attributable to different causes. By contrast, some GBS with reduced susceptibility to penicillin have been described, especially in Japan. In this group of bacteria, it is important to highlight that confirmation by reference methods is mandatory when decreased susceptibility to penicillin is suspected as well as checked for the detection of the mechanisms involved.

Group B streptococcal necrotizing pneumonia in a diabetic adult patient / Neumonía necrosante por estreptococo del grupo B en un paciente adulto diabético

The aim of this report is to describe a rare case of necrotizing pneumonia due to group B Streptococcus serotype III in a relatively young male adult (48 years old) suffering from diabetes. The organism was isolated from his pleural fluid and was only resistant to tetracycline. The patient first received ceftazidime (2 g/8 h i.v.) + clindamycin (300 mg/8 h) for 18 days and then he was discharged home and orally treated with amoxicillin clavulanic acid (1 g/12 h) for 23 days with an uneventful evolution. As in the cases of invasive infection by Streptococcus pyogenes, clindamycin could prevent streptococcal toxic shock syndrome.

El objetivo de esta presentación es describir un caso raro de neumonía necrosante debida a estreptococo del grupo B serotipo III en un diabético adulto de sexo masculino relativamente joven (48 años). El microorganismo fue aislado de líquido pleural y resultó ser resistente solo a tetraciclina. El paciente recibió ceftacidima (2 g/8 h iv) + clindamicina (300 mg/8 h) durante 18 días y luego fue dado de alta, bajo tratamiento oral con amoxicilina-ácido clavulánico (1 g/12 h). Este tratamiento se mantuvo durante 23 días, con buena evolución. Como en casos de infecciones invasivas por Streptococcus pyogenes, es posible que la clindamicina haya evitado la aparición del síndrome de shock tóxico estreptocócico.

Group B streptococcal necrotizing pneumonia in a diabetic adult patient.

The aim of this report is to describe a rare case of necrotizing pneumonia due to group B Streptococcus serotype III in a relatively young male adult (48 years old) suffering from diabetes. The organism was isolated from his pleural fluid and was only resistant to tetracycline. The patient first received ceftazidime (2g/8h i.v.)+clindamycin (300mg/8h) for 18 days and then he was discharged home and orally treated with amoxicillin clavulanic acid (1g/12h) for 23 days with an uneventful evolution. As in the cases of invasive infection by Streptococcus pyogenes, clindamycin could prevent streptococcal toxic shock syndrome.